This invention relates to providing vivid coloration and graphic intelligence to exposed lens retroreflective sheet constructions, and the resultant constructions.
Exposed lens retroreflective sheet constructions typically contain small spherical lens elements, i.e., small glass microspheres or bends hemispherically embedded in a suitable binder system, and specularly reflecting materials adjacent or on the rear surface of the lens elements, such as disclosed in U.S. Pat. Nos. 3,700,305 and 3,758,192. In use, as light is shined directly on the retroreflective material, the light is reflected back to the source and provides a great deal of illumination to the object containing the retroreflective material thereon. Such materials are commonly used in a variety of constructions, such as street and highway markings, as reflective portions on garments, etc.
The imparting of coloration and graphic intelligence to such retroreflective sheet materials has typically been undertaken by applying some to the backside of the sheet material and using transparent specular reflector and binder material. For example, in U.S. Pat. No. 3,700,305, the specular reflector and binder material can be transparent to light, such that by applying decorative effects to the backside of the sheet material, such effects can be visible under normal light.
Application of coloration via silk screening with colored inks, etc. to the exposed lens surface has been undertaken, but is undesirable in most instances, since retroreflection is virtually eliminated in the inked areas.
In commonly assigned U.S. application Ser. No. 695,974, filed June 14, 1976, there is disclosed a process for printing a colored image-containing transfer layer over a portion of the specularly reflective layer on the spherical lens elements, such that when transfer is undertaken to a substrate, the colored image-containing portions are effectively transferred and are also retroreflective.
It has now been found that a finished non-colored or white exposed lens retroreflective sheeting can be colored or a graphic intelligence imparted thereto by utilization of vapor dye transfer techniques. By utilizing such techniques an end-user can add coloration in-house to the sheeting instead of having to settle for add-on colorations or obtaining same from a supplier's limited selection.